2. Gillenia trifoliata (L.) Moench (mountain Indian physic, Bowman’s root)

Porteranthus trifoliatus (L.) Britton

Pl. 531 f, g; Map 2454

Stems 50–100 cm long, glabrous or sparsely hairy. Stipules 5–10 mm long, inconspicuous and usually shed soon after the leaves develop, linear, the margins smooth or more commonly with few glandular teeth, the upper surface glabrous or with sparse to moderate nonglandular hairs, usually also with scattered minute, stalked, dark-tipped glands, the undersurface with sparse to moderate nonglandular hairs. Leaflets 1.7–10.0 cm long, none of them deeply lobed, lanceolate or elliptic to oblong-oblanceolate, the margins sharply toothed, the upper surface glabrous or with sparse to moderate nonglandular hairs, usually also with scattered minute, stalked, dark-tipped glands, the undersurface with sparse to moderate nonglandular hairs. Hypanthium 5.5–8.0 mm long, glabrous or sparsely hairy. Petals 12–22 mm long. Fruits 5–8 mm long, sparsely to moderately hairy. 2n=18. May–June.

Known only from a single historical collection from Lawrence County (eastern U.S. west to Missouri and Arkansas; Canada [extirpated]). Margin of mesic upland forest on limestone substrate.

K. R. Robertson (1974) suggested that the Missouri specimen may represent an introduced population, but the mere proximity of a railroad to the site is insufficient evidence that the occurrence was nonnative, particularly as the species grows natively in northwestern Arkansas.